Priming mechanism for centrifugal pumps



PHIMING MECHANISM FOR CENTRIFUGAL PUMPS Filed Aug. 2, 1925 [N V/SNTOR fi. E Jkyfe fan 8) v mrma A TORNEY Patented Aug. 4, 1931 PATENT OFFICE UNITED STATES AIR/1'11'U'lt B. SINGLETON, OF DETROIT, MICHIGAN, ASSIGNOR TO NASH ENGINEERING CCMPANY, OF SOUTH NOBWALK, CONNECTICUT, A CORPORATION OF CONNECT- v ICUT PRIMING MECHANISM FOR CENTRIFUGAL PUMPS Application filed August 2, 1926. Serial No. 126,434.

This invention relates to mechanism for priming'a centrifugal pump, particularly of the' impeller type. Such pumps when operating under a negative head lose their pum 5 ing capacity as soon as air is admitted to t e pump chamber, which very often happens I when the pump is used for handling an irregular or inconsiderable flow of liquid.

It is the object of my invention to provide in improved priming mechanism for rendering the pump again operative, said priming mechanism being automatically limited in its action to the requirements of the system at any particular time. f

A further object is to provide a construction by which dirty or gritty water will be prevented from entering the priming air pump and will behandled only by the centrifugal water pump.

Another object of my invention is to provide mechanism for priming a centrifugal water pump which will automatically prevent flooding of the air pump after the water pump has become fully operative.

In the preferred form of my invention, the priming air pump is rendered partially inop erative when the water level above the centrifugal intake reaches a certain predetermined point, and thereafter maintains a deac gree of vacuum merely sufficient to maintain the water level for the centrifugal pump without causing a further rise of the water.

My invention further relates to arrangements and combinations of partswhich will 35 be hereinafter described and more particularly set forth in the appended claims. F

A preferred form of the invention is shown in the drawing, which is a side elevation, partly in" section, of a pumping apparatus embodying my invention. Referring to the drawing,-I have shown a separating tank 10 having an inlet pipe 11 from awater supply which is commonly at a I lower level than the tank 10. A centrifugal pump 12 has its inlet 13 extending into the lower part of the tank 10 and has a discharge pipe 14 through which water is discharged past a check valve 15 to any desired point of delivery.

. A priming air pump 20 is provided for the the side of the tank 10 and is also provided with an air inlet pipe 34 controlled by the valve 31.

The vacuum pump 20 is additionally provided with an air discharge pipe 36 and also preferably hasa separate water supply pipe 37 when the pump 20 is of the type using water for its pumping action. An' additional check valve 38 is also preferably placed in the vacuum connection 21.

fiaving described the details of construction of my improved pum ing apparatus, the functions and method 0 operation thereof are as follows:

It is well known that a centrifugal pump, whenever it loses its water supply, becomes air bound and that it is very diflicult and practicallyimpossible to cause such a pump to resume operations until the pump has been primed by withdrawing the air and admitting water to the pump casing. A primary function of the vacuum pump 20 is the priming of the casing of the centrifugal pump 12 by exhausting theair therefrom.

The'pump 20 serves an additional purpose,-

as it acts through its connection22 to assist the centrifugal pump in exhausting the air from the tank 10, causing the water to be pumped to rise into the tank 10 through the inlet pipe 11."

It is desirable, however, to limit the opera tion of the air pump 20, as otherwise some of the water from the tank 10 may enter the air pump through the connection 22 and the pipe 21. Certain types of air pump are seriously injured by permitting any considerable quantity of water to enter the pump, and other types of air pumps, such as those using water for the pumping action, while not injured by the admission of clear water, may be seriously damaged by the admission of watercontaining grit or sand, such as is frequently drawn into a separating tank as in dicated' at 10 and such as may be readily handled without injury by a Centrifugal pump.

I prevent the flow of water to the pump 20 by the operation of-the float controlled valve 31. As the water in the tank 10 reaches the predetermined level indicated by the line XX, the float 32 rises, opening the valve 31 and admitting air through the pipe 26 to the suction pipe 21 of the vacuum pump 20.

The pump 20 is thus limited in its operation and consumes less power than would otherwisebe required, as the degree of vacuum is v maintained at a predetermined point and never exceeds the requirements of. the system. When the water level falls below the line XX, the valve 31 again closes and the air pump increases the vacuum until the water level is again normal.

Whenever air is admitted through the valve 31, the check valve 25 immediately closes, thus preventing the air from flowing downward through the pipe 24 and venting the centrifugal pump 12. The check valve 38 prevents flow of air to the apparatus when the'vacuum pump 20 is not in operation. I I have thuspro'vided means by which the vacuum pump not only primes the centrifugal pump, but also assists in exhausting the f separating tank 10, and at the same time I have provided means for limiting the action of the vacuum pum when the water level is normal and for maintaining the water level in the tank 10 at a point where sand or gritty Water cannot be drawn over into the vacuum pump and injure the mechanismthereof.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed otherwise than as set forth in the claims, but what I claim is 1. Pumping. apparatus comprising a sep-' arating tank having an inlet connected to a source of lower lever water supply, a centrifugal water pump having a casing separate from said tank, said pump being connected to withdraw waterfrom said tank, an air pump having a connection to said tank and to said centrifugal pump casing, whereby to exhaust air therefrom, a float-controlled valve effective to admit air to partially disable said air pump when the water level. in the tank reaches a predetermined level, and a check valve to prevent reverse flow of air through the vacuum connections to'the centrifugal pump when said float valveis opened.

"2. Pumping apparatuscomprising a separating tank having an inlet connected to; a source of lower level water supply,,a centrifugal water pump havin a casing separate from said tank, said pump eing connected to withdraw water from said tank, an air pump havin a connectionf to said tank and to said centri ugal pump casing, whereby to exhaust air therefrom,- a float-controlled valve effective to admit air to partially disable the air pump when the water level in the tank reaches a predetermined level, and a check valve effective to prevent reverse flow of air through the connections to said tank and to said centrifugal pump when the air pump is inoperative. 1

3. Pumping apparatus comprising a tank having an inlet connected to a source of lower level water .supply, a centrifugal water pump having a casing separate from said tank, said pump being connected to withdraw water from said tank, an air pump connected to exhaust air from said tank and to cause flow of water from thelower level thereto, abranch connection from said air pump to said centrifugal pump casing for exhausting air therefrom, and means to vent said air pump when the water in said tank reaches a predetermined level.

4. Pumping apparatus comprising a' tank having an inlet connected to a source of lower level water supply, a centrifugal water pump separate from said tank and connected to withdraw water from said tank, an air pump connected to exhaust air from said tank and from the centrifugal pump, a float control valve effective to admit air \to partially disable said air pump as the water level in the tank reachesa predetermined level, and means to prevent reverse flow of air throughthe vacuum connections to the centrifugal pump upon opening of the float valve.

5 Pumping aparatus comprising a tank having an inlet connected to a source of lower I level water supply, a centrifugal water pump separate from. said tank and connected to withdraw water from the tank, an air pump connecte to exhaust air from said tank and from sai centrifugal pump, a float control valve eflective to admit air to partially disable the air pump when the water level in the tank reaches a predetermined level, and means effective to prevent reverse flow of air through the connections-to the tank and to the centrifugal pump when the air pump is inoperative. k

In testimony whereof I have hereunto affixed my signature.

ARTHURB. SIN GLETON. 

